Reactions in mixed non-aqueous solutions containing sulphur dioxide. Part 7. A Raman spectroscopic study of adduct formation between sulphur dioxide and dimethyl sulphoxide

Abstract

Details are given of the ν(SO)_dmso stretching (dmso = dimethyl sulphoxide), ν₁(SO₂), ν₃(SO₂), and ν₂(SO₂) regions of the Raman spectra of SO₂–dmso mixtures at 293 K and sub-ambient temperatures. Analysis of the ν(SO)_dmso region, which contains at least seven component bands, provides evidence of several component species. Bands at 1 067, 1 057, and 1 044 cm^–1 are due to monomers and associates of dmso, and a band whose frequency varies between 1 029 and 1 025 cm^–1 is due to a methyl-rocking mode of dmso. Bands at 1 013, 1 006, and 997 cm^–1 are attributed to the adducts SO₂·2dmso, SO₂·dmso, and 2SO₂·dmso respectively. An example of the use of band fitting to a difference spectrum supports these assignments.